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Control mechanism for a chair

This application is a divisional of U.S. application Ser. No. 11/598,166, filed Nov. 10, 2006, which is a continuation of PCT Application No. PCT/US06/07820, filed Mar. 1, 2006, which claims the benefit of U.S. Provisional Application Nos. 60/657,541, filed Mar. 1, 2005, and 60/689,723, filed Jun. 10, 2005.

The invention relates to an office chair and more particularly, to improvements in the tilt control mechanism of the office chair.

Conventional office chairs are designed to provide significant levels of comfort and adjustability. Such chairs typically include a base which supports a tilt control assembly to which a seat assembly and back assembly are movably interconnected. The tilt control mechanism includes a back upright which extends rearwardly and upwardly and supports the back assembly rearwardly adjacent to the seat assembly. The tilt control mechanism serves to interconnect the seat and back assemblies so that they may tilt rearwardly together in response to movements by the chair occupant and possibly to permit limited forward tilting of the seat and back. Further, such chairs typically permit the back to also move relative to the seat during such rearward tilting.

To control rearward tilting of the back assembly relative to the seat assembly, the tilt control mechanism interconnects these components and allows such rearward tilting of the back assembly. Conventional tilt control mechanisms include tension mechanisms such as spring assemblies which use coil springs or torsion bars to provide a resistance to pivoting movement of an upright relative to a fixed control body, i.e. tilt tension. The upright supports the back assembly and the resistance provided by the spring assembly thereby varies the load under which the back assembly will recline or tilt rearwardly. Such tilt control mechanisms typically include tension adjustment mechanisms to vary the spring load to accommodate different size occupants of the chair.

Additionally, conventional chairs also may include various mechanisms to control forward tilting of the chair and define a selected location at which rearward tilting is stopped.

Still further, such chairs include a pneumatic cylinder which is enclosed within a base of the chair on which the tilt control mechanism is supported. As such, the pneumatic cylinder is selectively extendable to vary the elevation at which the tilt control mechanism is located to vary the seat height. Such pneumatic cylinders include conventional control valves on the upper ends thereof and it is known to provide pneumatic actuators which control the operation of the valve and thereby allow for controlled adjustment of the height of the seat.

It is an object of the invention to provide an improved tilt control mechanism for such an office chair.

In view of the foregoing, the invention relates to a tilt control mechanism for an office chair having improved stop assemblies for forward tilt and rearward tilt as well as an improved pneumatic actuator for the chair. The front and rear stop assemblies cooperate with an interior control plate that is disposed within the control body and rotates in unison with a control shaft on which the uprights are supported. The front and rear stop assemblies selectively cooperate with this control plate to control forward tilting and rearward tilting of the chair.

Additionally, the pneumatic actuator assembly utilizes relatively rotatable cam blocks wherein rotation of one rotatable block relative to a fixed block causes vertical displacement of the rotatable block to depress the cylinder valve. Thus, the cooperating cam blocks convert horizontal displacement of the rotatable block into a corresponding vertical displacement thereof to actuate the valve. This rotatable block is driven by a conventional cable actuator that is in turn controlled by a flipper handle on the seat assembly.

Further, an improved actuator mechanism is provided for selectively actuating a rear stop assembly as well as a pneumatic cylinder actuator. This actuator assembly includes separate actuator handles for a front and rear stop assembly. The actuator handles are mounted on a common shaft and includes an improved over-center snap lock arrangement for the actuator handles. Still further, an improved cable connector for connecting the opposite end of each actuator cable to a respective bracket on the control housing.

These various mechanisms provide improved control to forward and rearward tilting of the seat and back assemblies and height adjustment thereof. Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.

FIG. 1 is a front elevational view of an office chair of the invention.

FIG. 2 is a side elevational view thereof.

FIG. 3 is a rear isometric view thereof.